How to ship by UPS

I selected UPS Ground as the shipping service for an auction. Auction has ended and when I click either to print shipping label or print packing slip, I get sent to PayPal where it asks me to enter an account number.

I entered my account number, which it SEEMS to recognize, but then it just displays the Enter Your Account number page.

There is always the option to ship it manually but taking it to the local UPS store or Staples, but I'd prefer not to pay the surcharge for that.

How does eBay's UPS shipping option actually work? i have noticed when i have an item marked to ship by UPS,  i go to print the shipping label from ebay,  and it directs me to paypal, then i have to sign in with my UPS account number and stuff,  but then when i get to page to print the label from paypal,  i always get a message saying  "sorry for the inconvenience,  but the system is not working at this time,  and can't print label",     so i always end up having to pay UPS store to print label for me instead,     and other people have said they have same problem trying to print label from paypal site also,   for a while now !,  

i guess it only lets you print your shipping label straight from ebay if its going by either USPS or FedEX only ?  but not UPS ?